Due to the global orientation of modern mechanical engineering companies having customers and machine users all over the world, it is helpful to provide maintenance, error diagnosis and, if necessary, also repair of the delivered machines, systems and devices (combined in the term “machines” below) not only directly on site, but also via remote access. Mainly large companies extend their Firewall gateways to virtual private network (VPN) portals through which the suppliers and system manufacturers can gain remote access to the delivered machines. In this connection, the suppliers and system manufacturers remove the local modems and ISDN accesses provided in their machines and systems. Some companies have defined access specifications that are not standardized. In addition to VPN, diverse other authentication methods are used, e.g., Caller-ID, Preshared Keys, One Time Password, or SecureID, or special hardware can be used.
Remote access using VPN sets high standards for the infrastructure and security. Remote access using VPN depends on the technology used by the machine user.